Go to walmart, pick up the Crosman Spring Shotgun (the tri shot one that's a clone of the TM, here in Canada $120 CAD so probably costs like $99 USD).
DO NOT get the single shot shotgun it's utter crap.
Also if you're in the North West the best place to go is probably AirsoftGI or Airsoft Extreme like I already told you. They're specialty stores and know their stuff and sell high quality products not normally found at Wallyworld.
Think of it like the difference between buying Gold Clubs at Canadian Tire (or Wally World) and going to a proshop. They cater to different people, if it's a weekend out with the boys you're looking for then Walmart Golf Clubs are probably good enough but if you want to do it for sport, very often, and possibly compete in Charity Tournaments or something then a proshop is probably where you want to buy your Clubs from.
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE